The subject application is directed to a system and method for employing an extended boundary lookup table. More particularly, the subject application is directed to a system and method for improving throughput in lookup table based conversions which tolerate input values that are out of table range.
Many systems employ lookup tables to allow for conversion of input values to corresponding output values. Lookup tables are used to output values such as physical characteristics associated with known physical systems in which inputs are empirically related to known, corresponding output values. Such tables are typically populated with values at discrete intervals. When an input value does not correspond with a table entry, it typically falls between entries that are available. In these instances, it is frequently desirable to complete an interpolation between bordering values to achieve a reasonable approximation of a corresponding output. Linear interpolation is commonly used, wherein two values define a line, and an interpolated value is calculated to be a value along that line, usually at a center point. While many physical properties have a relationship defined by a continuous function, assuming linear properties between discrete points is typically acceptable, and yields better results than if values are taken at a neighboring point of a predefined value.
Imaging systems, such as color imaging systems, frequently translate descriptions between color spaces. By way of example, many imaging systems will act in an additive color space, such as Red-Green-Blue (“RGB”) during image acquisition or processing. Output devices, such as laser printers or ink jet printers, typical render images in subtractive color spaces, such as Cyan-Magenta-Yellow-Black (“CMYK”). Translation between these color spaces is frequently done with the use of a lookup table, which process is enhanced by use of interpolation. Robust lookup table based conversion systems are able to handle situations where input values are out of lookup table range. In such systems, a test of each incoming value is made to determine whether it is in lookup table range. Such testing is time consuming, which is particularly problematic when thousands of conversions are completed as is frequently required in an image rendering operation.
Therefore, there is a need for a lookup table system and method that is able to handle out of range values, and avoids the necessity of completing a time consuming test of each input values. The subject application overcomes the above noted problems and provides a system and method for employing a lookup table having an extended boundary.